The present invention relates to torsional dampers.
Generators enable the conversion of mechanical energy from a prime mover into electrical energy, and are used in a variety of settings. For example, generators are commonly powered by gas turbine engines in order to generate electricity for an aircraft. With aerospace applications, gas turbine engines generally provide a variable speed rotational force that is input to a generator by means of suitable gearing.
Torsional instability, including that due to oscillations in rotational speed, is problematic for many generators. Torsional instability can contribute to fatigue failure of shafts and other mechanical components in the generator, prime mover, and any mechanical components linking the generator and prime mover. Many factors lead to torsional instability. For instance, known generators directly coupled to gas turbine engines typically produce relatively high torsional loads with little mechanical damping, and constant-power generator configurations also exhibit inversely proportional torque vs. speed curves (i.e., torque decreases with increasing operating speed). Changes in engine speed can produce relatively large oscillations in torque, resulting in large torsional oscillations experienced by generator components.
Active damping systems provided by generator controllers can provide generator torque oscillation damping, but at the undesirable cost of generator transient performance. Active damping can also require control hardware and control logic that add undesired complexity and cost. Mechanical spring-mass damper systems can also be used to dampen axial vibrations, but spring-mass damper systems must be tuned to relatively narrow frequency bands. Those factors reduce the effectiveness of spring-mass dampers with respect to generators that experience torque oscillations across a relatively wide frequency band.
Thus, an alternative torsional damper system for use with a generator is desired.